Lighting devices with a high luminosity density are known to be useful. A plurality of light emitting sources is usually assembled in a housing in order to increase luminosity density. However, as the density of light-emitting sources increases, the problem of waste heat and the need of efficient heat dissipation becomes an important issue.
LEDs (Light-emitting diodes) have become a popular choice of light-emitting sources due to its high electro-optical conversion efficiency as well as their long operating life span. However, it is well-known that the electro-optical conversion efficiency of an LED drops rapidly when temperature increases. Therefore, the problem of efficient heat dissipation management is especially noticeable for lighting devices comprising LEDs as lighting sources.
US 2004/0264195 describes an LED light source with a plurality of LEDs bonded to a heat sink with a printed circuit board surrounding the LED source and overlying the heat sink to mitigate degradation in light-emitting efficiency due to rising temperature. However, such an arrangement does not provide a satisfactory and/or sufficiently efficient heat dissipation scheme for efficient operation of a lighting device comprising a plurality of LEDs, especially a lighting device comprising plurality of LEDs in a relatively confined environment. Therefore, it would be desirable if there can be provided improved lighting devices with enhanced heat dissipation schemes or arrangements.